zmq_proxy_steerable(3)

SYNOPSIS

int zmq_proxy_steerable (const void *frontend, const void *backend, + const void *capture, const void *control);

DESCRIPTION

The zmq_proxy_steerable() function starts the built-in ØMQ proxy in the +current application thread, as zmq_proxy() do. Please, refer to this function +for the general description and usage. We describe here only the additional +control flow provided by the socket passed as the fourth argument "control".

If the control socket is not NULL, the proxy supports control flow. If +PAUSE is received on this socket, the proxy suspends its activities. If +RESUME is received, it goes on. If TERMINATE is received, it terminates +smoothly. At start, the proxy runs normally as if zmq_proxy was used.

If the control socket is NULL, the function behave exactly as if zmq_proxy +had been called.

Refer to zmq_socket(3) for a description of the available socket types. +Refer to zmq_proxy(3) for a description of the zmq_proxy.

EXAMPLE USAGE

cf zmq_proxy

RETURN VALUE

The zmq_proxy_steerable() function returns 0 if TERMINATE is sent to its +control socket. Otherwise, it returns -1 and errno set to ETERM (the +ØMQ context associated with either of the specified sockets was terminated).

EXAMPLE

Creating a shared queue proxy

//  Create frontend, backend and control sockets
+void *frontend = zmq_socket (context, ZMQ_ROUTER);
+assert (backend);
+void *backend = zmq_socket (context, ZMQ_DEALER);
+assert (frontend);
+void *control = zmq_socket (context, ZMQ_SUB);
+assert (control);
+
+//  Bind sockets to TCP ports
+assert (zmq_bind (frontend, "tcp://*:5555") == 0);
+assert (zmq_bind (backend, "tcp://*:5556") == 0);
+assert (zmq_connect (control, "tcp://*:5557") == 0);
+
+// Subscribe to the control socket since we have chosen SUB here
+assert (zmq_setsockopt (control, ZMQ_SUBSCRIBE, "", 0));
+
+//  Start the queue proxy, which runs until ETERM or "TERMINATE"
+//  received on the control socket
+zmq_proxy_steerable (frontend, backend, NULL, control);

Set up a controller in another node, process or whatever

void *control = zmq_socket (context, ZMQ_PUB);
+assert (control);
+assert (zmq_bind (control, "tcp://*:5557") == 0);
+
+// pause the proxy
+assert (zmq_send (control, "PAUSE", 5, 0) == 0);
+
+// resume the proxy
+assert (zmq_send (control, "RESUME", 6, 0) == 0);
+
+// terminate the proxy
+assert (zmq_send (control, "TERMINATE", 9, 0) == 0);
+---
+
+
+SEE ALSO

zmq_proxy(3) +zmq_bind(3) +zmq_connect(3) +zmq_socket(3) +zmq(7)

AUTHORS

This page was written by the ØMQ community. To make a change please +read the ØMQ Contribution Policy at http://www.zeromq.org/docs:contributing.